Lamp and ballast holder



Dec. 3, 1963 c, CUTLER 3,112,891

LAMP AND BALLAST HOLDER Filed July 28, 1961 Irv/an hor: CLaw-ence M. Ll GlfiT 9 His A t lrovneg United States Patent 3,112,891 LAMP AND BALLAST HOLDER Clarence M. Cutler, Euclid, Ohio, assignor to General Electric Company, a corporation of New York Filed July 28, 1961, Ser. No. 127,544 7 Claims. (Cl. 240-51.12)

The present invention relates to a combined ballast housing and lamp holder for a fluorescent panel lamp having an integral or permanently attached ballast.

Fluorescent panel lamps are discharge lamps operating on the same principle as the common elongated fluorescent lamp but wherein the discharge occurs in a labyrinthine channel formed between two vitreous components sealed together along their margins. Such lamps provide a relatively long discharge in a small area which is an advantage from the point of view of compactness of source and ease of handling. They oifer what may be described as an area light source as against a line source as is the case with the usual elongated fluorescent lamp. Although the bare concept of a fluorescent panel lamp is quite old, it is only by reason of recent improvements in structure and in processing methods and techniques that such lamps are now reaching the stage of a practical light source. These improved panel lamps and methods for making them are described and claimed in copending application Serial No. 106,829, filed May 1, 1961, by Richard S. Christy, entitled Panel Lamp and Manufacture Thereof, and assigned to the same assignee as the present invention.

One of the attractive features of thepfluorescent panel lamp is its adaptability to an integral ballast combination. Being a discharge lamp with a negative impedance characteristic, the fluorescent panel lamp, like any other fluorescent lamp, must be provided with some current regulating means generally known as a ballast. By providing a hole in the center of a panel lamp, space becomes available wherein to mount a ballast which may be permanently attached to the lamp in an integral construction. Such a unit may then be connected directly to the usual alternating current supply in about the same fashion as an incandescent lamp. In the case of a round panel lamp, the hole in the center may be circular, the bare lamp having somewhat the shape of a broad Washer. Inthe case of a square panel la-mp, the central hole may be square.

The general object of my invention is to provide an attachment and holder for a fluorescent panel lamp having a ballast integrally attached thereto, to support the lamp and facilitate electrical connections thereto and preferably serve as a housing for the ballast, and which is convenient to use and attractive in appearance.

The objectives sought to be accomplished and which led to my present invention are as follows. It is desired to support the lamp-ballast unit independently of the electrical connections to the unit. The holder must maintain the unit in place but must not put any strain on the lamp while it is being mounted or locked in place. It

is desirable to have an arrangement which does not require that the lamp be maneuvered or rotated in order to lock it in place. With some mounting arrangements, and in particular with a square panel lamp, it is often not feasible to rotate the lamp.

A desirable feature of a holder for an integral ballast panel lamp is capability of holding the lamp with one hand and locking it into position with the other hand. Preferably the central space in which the ballast components areto be mounted should be kept free from a central rod; by so doing, more latitude for the placement and insulation of the ballast elements is available and a more compact construction is made possible. Desirably anassi Patented Dec. 3, 1963 "ice ventilation should be provided in order to cool the ballast components. Finally the electrical connections should be in a protected place so as to minimize shock hazard in installation.

in accordance with the invention, 1 provide a holder for a fluorescent panel lamp of the centrally apertured kind which permits the lamp to be lifted up and fastened to a ceiling bracket without requiring any twisting or v turning of the lamp proper, and which simultaneously makes electrical connections between the ballast forming an integral part of the lamp and cooperating line terminals in the bracket. This is accomplished by means of a support member which interengages the lamp proper and the bracket and which is provided with limited freedom of movement relative to the lamp sufficient to permit locking to the bracket.

In a preferred embodiment, the support member forms a housing surrounding the ballast and can be turned relative to the lamp by means of a bottom plate attached thereto. By twisting the bottom plate, the housing is locked to the ceiling bracket, all without putting any strain on the lamp. Suitable apertures are provided so that the housing serves as a chimney surrounding the ballast which is cooled by convection flow of air.

For other features and for a better understanding of the advantages of the invention, attention is now directed to the following detailed description of a preferred embodiment to be taken in conjunction with the accompanying drawing. The features of the invention believed to be novel will be more particularly pointed out in the appended claims.

In the drawings:

FIG. 1 is a top plan view of a round fluorescent panel lamp.

FIG. 2 is a side view, partly sectioned, of the same lamp but with the integral ballast shown mounted in the center.

FIG. 3 is a vertically exploded pictorial view showing the component parts of a holder for the lamp embodying my invention.

1 16. 4 is a side elevation, partly sectioned, through the assembled holder.

Referring to the drawing and more particularly to FIGS. 1 and 2, the round fluorescent panel lamp 1 is formed by a pair of circular or disc-like complementary molded glass components consisting of the faceplate 2 and the backplate 3. The plates are fused together in a ledge seal at their inner and outer peripheries 4, 5. A tortuous discharge channel is defined by means of three concentric grooves 6 in the backplate which revert at 7 to form a continuous channel extending between electrodes 8, 9 located at the ends of the channel near the inner periphery. The faceplate may be provided with complementary shallow grooves which, as illustrated, are broken up into shallow embossments 10 resulting in a quilted pattern which improves the appearance and increases the strength of the assembly. The margins of the two plates may be fused together by heating the glass above its strain point but not to conventional softening temperature, and applying a very high pressure thereto followingthe teachings of copending application Serial No.lO-6,829, filed May 1, d961, of Richard S. Christy, entitled Panel Lamp and Manufacture Thereof, and assigned to the same assignee as the present invention. At the internal junctures between the valleys 11 in the backplate and the flat areas or lands 12 between embossments in the faceplate, the glass surfaces are merely pressed together into close conformance by the application of relatively low pressure but are not sea-led or fused together. Provided there is close conformance of the glass surfaces along the junctures, the electric discharge 3 will not leak through and short circuit at the junctures, but will follow the tortuous channel through from end to end.

The lamp is provided with an ionizable filling consisting of a small quantity of mercury and an inert starting gas such as argon at a pressure of 2 to 3 millimeters of mercury. The lamp envelope is coated internally with phosphor indicated at 13 which is excited by the 2537 A. radiation resulting from the dischange through the mercury vapor, to produce visible light. In order to have the lamp emit a greater proportion of its light downwardly through the faceplate than through the backplate, a thin ner phosphor coating may be applied to the former.

The discharge support-ing electrodes 8, 9 located at opposite ends of the channel each comprises a tungsten filament coated with electron-emitting alkaline earth oxides. The filament is supported across the inner projections of inleads 14 which are sealed through the glass of the ledge seal at the inner periphery 4. The outer projections or" the inleads are connected to a ballast or current regulating means located within the can 16.

The principal function of the ballast is to determine the operating current through the lamp. In addition it must provide heating current to the lamp electrodes, either at starting only or during operation depending upon the type of circuit, and it must provide a sufliciently high open-circuit voltage, in respect of the lamp environtrfi'iit, to start the lamp. The ballast may be any of those suitable for operating fluorescent discharge lamps. However I prefer to use a rectifier-capacitor bridge circuit because of its light weight and eificiency. Such a circuit comprises a pair of branches each including a rectiher and a capacitor connected in series across AG. input terminals, the rectifiers being poled for conduction in opposite directions in the two branches. The utilization circuit, which includes the lamp in series with a small inductance is connected across the junction points of the rectifier and capacitor in each branch. Desirably the ballast circuit constants are such that the lamp operates in a bimodal impedance mode at twice the line frequency and the current through the lamp is unidirectional with a superimposed alternating component having a fundamental frequency of twice the line frequency. Such ballast circuits are described and claimed in copending application Serial No. 106,503, filed April 25, 1961, of William H. Lake, entitled Discharge Lamp Ballasting Circuit and assigned to the same assignee as the present invention. Since the current through the lamp with this ballast is unidirectional, the lamp is desirably provided with mercury feedback passages between the electrode regions in order to prevent cataphoretic accumulation of mercury at the cathode and depletion at the anode. Panel lamps having mercury feedback passages of this kind are described and claimed in copending application Serial No. 111,029, filed May 18, 1961, of William H. Lake, entitled Low Pressure Mercury Vapor Discharge Lamp for Direct Current Operation, and assigned to the same assignee as the present invention.

The ballast components are housed within the cylindrical can '16 which is provided at its lower end with an outwardly turned rim or skirt 17. The ballast can is permanently attached to the lamp to form an integral unitary structure there-with by engagement with ledge seal 4 at the inner margin. In the illustrated embodiment, this is accomplished by having the outer edge of skirt 17 seat on the inner ledge seal 4 of the lamp. :A metal ring 18 engages the underside of the lamp rim and is provided with upwardly directed tabs 19 which enter into cooperating slots 20 in the skirt. The tabs are partially slit near their upper ends as seen at 21 and the tabs are locked in the slots by twisting or bending over the slit portions. The connection of the electrode inleads 14 to the ballast components within the can are made at the time when the can is permanently attached to the lamp. #In order to prevent rotation between the ballast can and the lamp which might place strain on the electrode inleads, the inner ledge seal 4 of the lamp may be provided with notches 19' which cooperate with and engage tabs 19 of the retaining ring 18. Instead of using a locking ring, the skirt 17 may be cemented to the inner rim of the lamp.

The terminals for AC. energization of the ballast components are in the form of a pair of insulated studs 22 projecting through the top of the ballast can. The studs are designed to engage a pair of spring loaded line contacts 23 in ceiling bracket 24. Contacts 23 are per manently connected to the building wiring by means of insulated conductors 25. The springs 26 insure positive contact between ballast terminal '22 and line contact 23 and at the same time serve to provide a down-ward force against the ballast to lock it more firmly in place.

The lamp-ballast unit is secured to the ceiling bracket by means of a support member or housing 28 in the form of a cylindrical shell. It is proportioned to surround the ballast can with an annular air space in between forming a ventilating passageway. At its upper rim, the housing is provided with three L-shaped slots 29 which engage cooperating pins 30 projecting from the sides of ceiling bracket 24. Thus a twist-lock engagement is effected between housing 28 and ceiling bracket 24- which is made secure when the pins enter the upwardly extending enlargements 31 at the inner ends of the slots.

At its lower end, housing 28 is provided with downwardly extending lugs 32 which project through oversize arcuate slots 33 in skirt 17 and engage in cooperating slots 34- in bottom plate 35. The shoulders at 36 in lugs 32 seat on the top face of plate 35, and the housing and bottom plate are locked together by bending over the slit ends 3-7 of the lugs.

The lugs 32 of the housing pass through the oversize slots 33 in skirt 17 of the ballast can and clear the inside edge of locking ring 18. Thus the housing 28 is free to rotate relative to the lamp and ballast can within the limits imposed by the dimension of oversize slots 33 relative to lugs 32. The lamp-ballast unit may be secured to the ceiling bracket by the simple expedient of pressing it upward into place with one hand while the other hand is used to twist the bottom plate and effect the twist lock. No strain is imposed on the lamp and there is no need to rotate the lamp relative to the ceiling bracket.

With the ballast located in the center of the lamp, it is particularly desirable to provide some elfective cooling arrangement for the ballast. According to a feature of the invention, housing 28 lends itself to a very elfective arrangement. Lateral ventilating holes 38 are provided in it near its upper end, and ventilating holes are also provided at 39 in skirt 17 of the ballast 16 and at 40 in bottom plate 35. The holes in the bottom plate are arranged to line up with those in the skirt of the ballast can when the unit is properly assembled and locked to the ceiling bracket. A chimney efiect is provided by the housing whereby cool air is drawn up through the bottom holes 39, 40, passes through the annular space and out through the top holes 38, as indicated by the arrows 41 in FIG. 4. For additional cooling, the bottom plate 35 may also be provided with holes near its center, as indicated at 42 in FIG. 4 allowing additional flow of air along the bottom side of the ballast can as indicated by arrow 43. Desirably the bottom plate is figured or patterned for appearance and in order to facilitate twisting. As illustrated, this is achieved by providing segmental indentations 44 which serve also as finger grips.

The invention has been described by reference to a round fluorescent panel lamp. However, with minor modifications, it is adaptable to a square panel lamp having a square aperture in the center. In such case, the skirt of the ballast can and the locking ring which fastens the lamp thereto would naturally be squared oif to match the square hole in the lamp. The ballast housing may be square for the most part but with a circular adapting portion at the top end to engage the ceiling bracket. At the bottom end of the housing, four downwardly extending lugs may be provided turning in arcuate slots in the four sides of the square skirt of the ballast can. The bottom plate is preferably made square and lines up with its sides parallel to those of the lamp when the unit is locked in.

The illustrated in embodiment is of course to be considered an example of the invention only and modifications will readily occur to those skilled in the art. It is intended by the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a fluorescent panel lamp comprising a vitreous envelope formed of a backplate and a faceplate sealed together along their margins in a ledge seal and having an opening in the center, a ballast structure permanently attached to said lamp and mounted Within said opening and including parts engaging the ledge seal of the lamp at said opening, a housing surrounding said ballast structure and having downwardly extending periph eral portions projecting through oversize openings in said parts, a bottom plate attached to said portions below said parts which upon being twisted, causes said housing to turn relative to said lamp and ballast structure, a bracket, and means at the upper end of said housing engaging cooperating means on said bracket for locking said housing to said bracket by twisting said bottom plate relative to said lamp.

2. A combination as defined in claim 1 and including ventilating apertures in said housing near its upper end and cooperating ventilating apertures in said bottom plate to allow convection flow of cooling air around said ballast structure within said housing.

3. In combination, a fluorescent panel lamp comprising a vitreous envelope formed of a backplate and a faceplate sealed together along their margins in a ledge seal and having an opening in the center, a ballast structure permanently attached to said lamp and mounted within said opening and including parts engaging the ledge seal of the lamp at said opening, a housing surrounding said ballast structure and having downwardly extending lugs projecting through oversize openings in said parts, a bottom plate attached to said lugs below said parts which, upon being twisted, causes said housing to turn through a limited angle relative to said lamp and ballast structure, a ceiling bracket, and means at the upper end of said housing engaging cooperating means on said ceiling bracket for locking said housing to said bracket by twisting said bottom plate relative to said lamp.

4. In combination, a fluorescent panel lamp comprising a vitreous envelope formed of a backplate and faceplate sealed together along their margins in a ledge seal and having an opening in the center, a ballast structure located within said opening, said ballast structure being provided with a skirt-like member engaging and attached to the ledge seal of the lamp at said opening, a housing surrounding said ballast structure and having downwardly extending lugs projecting through oversize openings in said member, a bottom plate attached to said lugs below said member which, upon being twisted, causes said housing to turn relative to said lamp and ballast structure, a ceiling bracket, and means at the upper end of said housing engaging cooperating means on said ceiling bracket for locking said housing to said bracket by twisting said bottom plate relative to said lamp.

5. A combination as defined in claim 4 and including ventilating apertures in said housing near its upper end and cooperating ventilating apertures in said member to allow convection flow of cooling air through said housing.

6. In combination, a round fluorescent panel lamp comprising a vitreous envelope formed of a circular backplate and faceplate sealed together along their margins in a ledge seal and having a circular opening in the center, a ballast structure mounted in a can within said opening, said ballast can having an outwardly turned skirt seating on the ledge seal of the lamp at said opening, a locking ring fastened to said skirt and engaging the underside of said ledge seal, a housing surrounding said ballast can and having downwardly extending lugs projecting through arcuately oversize slots in said skirt, a bottom plate attached to said lugs below said skirt which, upon being twisted, causes said housing to turn relative to said lamp and ballast structure, a ceiling bracket, and means at the upper end of said housing engaging cooperating means on said ceiling bracket for locking said housing to said bracket by twisting said bottom plate relative to said lamp.

7. A combination as defined in claim 6 and including ventilating apertures in said housing near its upper end and cooperating aligned ventilating apertures in said skirt and bottom plate to allow convection flow of cooling air in the annular space between said housing and ballast can.

Jones July 26, 1949 Fry Mar. 17, 1959 

1. IN COMBINATION, A FLUORESCENT PANEL LAMP COMPRISING A VITREOUS ENVELOPE FORMED OF A BACKPLATE AND A FACEPLATE SEALED TOGETHER ALONG THEIR MARGINS IN A LEDGE SEAL AND HAVING AN OPENING IN THE CENTER, A BALLAST STRUCTURE PERMANENTLY ATTACHED TO SAID LAMP AND MOUNTED WITHIN SAID OPENING AND INCLUDING PARTS ENGAGING THE LEDGE SEAL OF THE LAMP AT SAID OPENING, A HOUSING SURROUNDING SAID BALLAST STRUCTURE AND HAVING DOWNWARDLY EXTENDING PERIPHERAL PORTIONS PROJECTING THROUGH OVERSIZE OPENINGS IN SAID PARTS, A BOTTOM PLATE ATTACHED TO SAID PORTIONS BELOW SAID PARTS WHICH UPON BEING TWISTED, CAUSES SAID HOUSING TO TURN RELATIVE TO SAID LAMP AND BALLAST STRUCTURE, A BRACKET, AND MEANS AT THE UPPER END OF SAID HOUSING ENGAGING COOPERATING MEANS ON SAID BRACKET FOR LOCKING SAID HOUSING TO SAID BRACKET BY TWISTING SAID BOTTOM PLATE RELATIVE TO SAID LAMP. 